Waterways such as rivers or other bodies of water often contain natural channels whose depth is sufficient for safe navigation. Over time, however, natural channels tend to accumulate silt on their bottoms, thereby reducing their depth. Given enough time, river action, tidal action and the cumulative effect of different weather conditions, a channel can become so silted as to render it unfit for navigation. In order to keep channels navigable, dredging is used to reduce the amount of silt on the bottom of the channel. However, due to the action of water currents, an area wider than the area used for navigation must be dredged to be effective. As a result, even if the desired channel is only 10 or 20 meters wide, a path 30 meters or more wide would need to be dredged to ensure that the central 10 or 20 meters is clear. In many cases, water currents and tidal action cause the rapid accumulation of silt, necessitating almost annual dredging of the channel. Building walls around the channel would be too expensive, and would likely fail due to hydro-dynamic forces. Therefore, a less expensive and simple method of keeping navigation channels free from silt is required.
One possible solution to reduce the need for dredging in waterways is the use of aquatic curtains. There are generally two types of curtain configurations known in the art. One is a floating suspension type curtain which does not extend to the bottom of the waterway. By sitting above the bottom of a waterway, key objectives are to promote the more efficient settling of suspended particles to the bottom of the waterway (from where they were previously disturbed as a result of man-made activity) and to minimize negative impacts on natural aquatic systems.
Another known curtain configuration is a floating curtain which is staked or similarly anchored to the bottom of a waterway. Such curtain systems tend to include a significant excess of curtain slack to compensate for wave turbulence and other water level fluctuations. This can result in significant leakage. When used to bind off bodies of water on either side of the curtain barrier, one way to minimize leakage is to use anchoring and curtain segment attachment mechanisms, as disclosed in U.S. Pat. No. 4,100,746. The application of such known curtain devices is generally limited to containment to prevent the movement of material and fluid from a contained body of water to facilitate various activities. For example, Triton Turbidity Curtains by GEI Works can be used to facilitate dredging, construction and dock/harbour maintenance. These kinds of curtain devices, however, do not provide or facilitate the transport of silt and similar debris from one bottom area of a waterway to another bottom area or to the bank of a waterway.
There are also known curtain devices which allow for the filtration of suspended particles to prevent their passage across the curtain barrier, while allowing for the passage of water through the curtain (e.g., Gunderboom aquatic filter barrier systems). Given the objective of material containment, these kinds of curtain devices are not designed to support the creation of navigable artificial channels within natural waterways, that can also remain free of silt build-up (i.e., be self-cleaning). Moreover, such known curtain devices are, typically, physically attached to the bottom of a waterway in order to withstand extreme water forces when performing their filtration function.
Accordingly, known curtain configurations present certain disadvantages and limitations with respect to: i) silt and current flow management in waterways, ii) supporting the improved navigation of waterways where different entry and exit points into an artificial channel, or bound off body of water may be required; and iii) the leveraging of current/water flow in a waterway as a resource, for example, to generate hydroelectric power.
With the foregoing in view, and other advantages as will become apparent to those skilled in the art, the invention is herein described by reference to the accompanying drawings forming a part hereof and certain exemplary embodiments.